YAML is the correct option.

YAML is the typical file format used to author Kubernetes Pod manifests because it is human readable and it maps directly to the same structured data that the API accepts as JSON. Most official examples and tutorials show manifests in YAML and kubectl commonly applies files written in YAML. YAML also supports comments which makes long manifests easier to document and maintain.

JSON is technically supported by the Kubernetes API and you can submit manifests as JSON. It is not the typical authoring format on exams and examples because it is less convenient to write by hand than YAML.

HCL is the HashiCorp Configuration Language used by Terraform and other HashiCorp tools. It is not used to author Kubernetes Pod manifests and kubectl does not accept HCL files as manifests.

XML is not a supported manifest format for Kubernetes Pod definitions. The Kubernetes API expects structured data expressed as YAML or JSON and XML is not used in normal workflows.

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